The present invention relates to a novel method of manufacturing halogenated .alpha.-aminoketones and .alpha.-aminoalcohols of the formula ##STR2## wherein X is halogen; one of Q.sup.1 and Q.sup.2 is hydrogen and the other is hydroxy, or Q.sup.1 and Q.sup.2 together are oxo; R.sup.1 is an amino protecting group; and R.sup.2 is hydrogen or the characterizing group of an .alpha.-aminocarboxylic acid.
Generally, the process comprises
a) reacting an ester of formula ##STR3## wherein R.sup.3 is lower-alkyl, and R.sup.1 and R.sup.2 are as defined above,
with a lower-alkyl-lithium and an organochlorosilane of the formula ClSi(R.sup.4,R.sup.5,R.sup.6), wherein R.sup.4, R.sup.5 and R.sup.6 are each independently selected from lower-alkyl and phenyl, to yield the compound of formula ##STR4## wherein R.sup.1 -R.sup.6 are as defined above; and
b) reacting the silyl-protected compound of formula III with dihalogenated methane and a lower-alkyl-lithium to yield a compound for formula I.
The compounds of formula I, which are described e.g. in J. Med. Chem. 1990, 33, 1285-1288 and in European Patent Publication 0 432 695, and, respectively, in U.S. Pat. No. 5,196,438, are valuable intermediates for the manufacture of pharmacologically active compounds, particularly compounds for the treatment of viral infections.